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  • Question
  • What will be the output of the program?
    public class Switch2 
    {
        final static short x = 2;
        public static int y = 0;
        public static void main(String [] args) 
        {
            for (int z=0; z < 3; z++) 
            {
                switch (z) 
                {
                    case x: System.out.print("0 ");
                    case x-1: System.out.print("1 ");
                    case x-2: System.out.print("2 ");
                }
            }
        }
    }
    


  • Options
  • A. 0 1 2
  • B. 0 1 2 1 2 2
  • C. 2 1 0 1 0 0
  • D. 2 1 2 0 1 2

  • Correct Answer
  • 2 1 2 0 1 2 

    Explanation
    The case expressions are all legal because x is marked final, which means the expressions can be evaluated at compile time. In the first iteration of the for loop case x-2 matches, so 2 is printed. In the second iteration, x-1 is matched so 1 and 2 are printed (remember, once a match is found all remaining statements are executed until a break statement is encountered). In the third iteration, x is matched. So 0 1 and 2 are printed.

    More questions

    • 1. Which statement is true?

    • Options
    • A. catch(X x) can catch subclasses of X where X is a subclass of Exception.
    • B. The Error class is a RuntimeException.
    • C. Any statement that can throw an Error must be enclosed in a try block.
    • D. Any statement that can throw an Exception must be enclosed in a try block.
    • Discuss
    • 2. What will be the output of the program?
      import java.util.*;
      public class NewTreeSet2 extends NewTreeSet 
      {
          public static void main(String [] args) 
          {
              NewTreeSet2 t = new NewTreeSet2();
              t.count();
          }
      }
      protected class NewTreeSet
      {
          void count() 
          {
              for (int x = 0; x < 7; x++,x++ ) 
              {
                  System.out.print(" " + x);
              }
          }
      }
      

    • Options
    • A. 0 2 4
    • B. 0 2 4 6
    • C. Compilation fails at line 2
    • D. Compilation fails at line 10
    • Discuss
    • 3. What will be the output of the program?
      int x = 3; 
      int y = 1; 
      if (x = y) /* Line 3 */
      {
          System.out.println("x =" + x); 
      }
      

    • Options
    • A. x = 1
    • B. x = 3
    • C. Compilation fails.
    • D. The code runs with no output.
    • Discuss
    • 4. What will be the output of the program?
      public static void main(String[] args) 
      {
          Object obj = new Object() 
          {
              public int hashCode() 
              {
                  return 42;
              }
          }; 
          System.out.println(obj.hashCode()); 
      }
      

    • Options
    • A. 42
    • B. Runtime Exception
    • C. Compile Error at line 2
    • D. Compile Error at line 5
    • Discuss
    • 5. What will be the output of the program?
      public class SyncTest 
      {
          public static void main (String [] args) 
          {
              Thread t = new Thread() 
              {
                  Foo f = new Foo();
                  public void run() 
                  {
                      f.increase(20);
                  }
              };
          t.start();
          }
      }
      class Foo 
      {
          private int data = 23;
          public void increase(int amt) 
          {
              int x = data;
              data = x + amt;
          }
      }
      
      and assuming that data must be protected from corruption, what?if anything?can you add to the preceding code to ensure the integrity of data?

    • Options
    • A. Synchronize the run method.
    • B. Wrap a synchronize(this) around the call to f.increase().
    • C. The existing code will cause a runtime exception.
    • D. Synchronize the increase() method
    • Discuss
    • 6. What is the most restrictive access modifier that will allow members of one class to have access to members of another class in the same package?

    • Options
    • A. public
    • B. abstract
    • C. protected
    • D. synchronized
    • E. default access
    • Discuss
    • 7. Which of the following statements is true?

    • Options
    • A. If assertions are compiled into a source file, and if no flags are included at runtime, assertions will execute by default.
    • B. As of Java version 1.4, assertion statements are compiled by default.
    • C. With the proper use of runtime arguments, it is possible to instruct the VM to disable assertions for a certain class, and to enable assertions for a certain package, at the same time.
    • D. When evaluating command-line arguments, the VM gives -ea flags precedence over -da flags.
    • Discuss
    • 8. What will be the output of the program?
      public class Switch2 
      {
          final static short x = 2;
          public static int y = 0;
          public static void main(String [] args) 
          {
              for (int z=0; z < 3; z++) 
              {
                  switch (z) 
                  {
                      case x: System.out.print("0 ");
                      case x-1: System.out.print("1 ");
                      case x-2: System.out.print("2 ");
                  }
              }
          }
      }
      

    • Options
    • A. 0 1 2
    • B. 0 1 2 1 2 2
    • C. 2 1 0 1 0 0
    • D. 2 1 2 0 1 2
    • Discuss
    • 9. Which is the valid declarations within an interface definition?

    • Options
    • A. public double methoda();
    • B. public final double methoda();
    • C. static void methoda(double d1);
    • D. protected void methoda(double d1);
    • Discuss
    • 10. Suppose that you would like to create an instance of a new Map that has an iteration order that is the same as the iteration order of an existing instance of a Map. Which concrete implementation of the Map interface should be used for the new instance?

    • Options
    • A. TreeMap
    • B. HashMap
    • C. LinkedHashMap
    • D. The answer depends on the implementation of the existing instance.
    • Discuss


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